An ultrasonic diagnostic apparatus transmits an ultrasonic beam from an ultrasonic probe to a subject and, on the basis of a reception signal received from the subject, obtains information necessary for diagnosis. In particular, high image capturing speed of ultrasonic image capturing can be utilized for a region whose motion is fast like the heart in a living body more than other image capturing methods such as image capturing methods using X-ray CT, MRI, and the like.
A change in the thickness of cardiac muscle accompanying beating is an element useful for examining various diseases of the heart, and measurement of a change in the thickness of cardiac muscle on an ultrasonic slice image is conventionally widely performed (refer to, for example, Japanese Patent Application Laid-Open No. 2001-70303).
In the case where the condition of a patient having ischemic heart disease is worsened, a region in which the thickness of the cardiac muscle is reduced is determined as a lesion. When attention is paid to the change rate of the thickness of cardiac muscle accompanying beating, before a condition becomes serious to an extend that the thickness of the cardiac muscle is reduced, the lesion can be detected. It becomes also possible to grasp the condition of the disease, so that measurement of the thickness of the cardiac muscle is valuable from the clinical point of view.